This is a proposal from the Massachusetts Institute of Technology for an extension of Grant No. RR-00995-03 for a period of five years for the support of a National NMR Facility for Biomolecular Research located at the Francis Bitter National Magnet Laboratory. The overall mission of the Facility is: (1) to develop, operate and maintain state of the art superconducting NMR spectrometer systems; (2) to provide these advanced NMR research facilities for collaborative projects and visitors; (3) to carry out in-house basic and applied research centered on biomedical applications of high field NMR spectroscopy; (4) to train biomedical investigators and others in NMR applications as collaborators and external users. To help accomplish these objectives the Facility will be equipped with four high field superconducting NMR spectrometers which have comprehensive utility and flexibility for biomolecular research. They operate in the pulse excited, Fourier transform mode with versatile pulse programmers, multi-nuclei observe capability and can accommodate various sample sizes (5-25 mm). These instruments will permit the various types of double resonance and relaxation time studies important to investigations of biological materials to be performed. We plan to carry on a milestone development effort to achieve a 150 kG (640 MHz), Nb3Sn multifilamentary superconducting magnet system operating in the persistent mode. We aim to strengthen our in-house and collaborative research capability and to focus on NMR studies of natural and model membrane structure, dynamics, function, phase diagrams, phase transitions; solution conformation of insulin and mechanism of action; dynamics of energy metabolism in the myocardium. Due to the unique combination of instruments and personnel planned for the next five years this NMR resource will have exceptional capabilities for studying the diverse materials important in biological processes.